Air quality enters unhealthy levels as 3-hour PSI breaches 100

SINGAPORE — Air quality reached unhealthy levels today as the three-hour Pollutant Standard Index (PSI) climbed steadily throughout the day to breach 100. The three-hour PSI peaked at 6pm at 106, before dipping out of the unhealthy range at 8pm with a reading of 99.

The 24-hour PSI at 6pm was 70 to 93.

The National Environment Agency (NEA) said that the PM2.5 levels were elevated in most regions of Singapore. 

“The haziness is likely due to an accumulation of increased particulate matter in the atmosphere under light wind conditions throughout today. Burning activities in the Northern Asean region, Peninsular Malaysia and Sumatra could have contributed to the increased concentration of particulate matter,” said the NEA in an advisory.

Current hazy conditions are expected to persist for the rest of today. 

Graph showing 3-hour PSI readings increasing today and peaking at 6pm before dipping out of the unhealthy range at 8pm. Source: www.haze.gov.sg

The NEA said that for tomorrow, the prevailing winds are expected to be light and variable in direction, and hazy conditions can still be expected. The 24-hr PSI for Singapore is expected to be in the moderate range.

Given the air quality forecast for the next 24 hours, everyone can continue with normal activities, the NEA said, but noted that the health impact of haze is dependent on one’s health status, the PSI level, and the length and intensity of outdoor activity.

From 1am, the three-hour PSI reading was in the 60s, reaching 71 at 11am, 74 at noon and 80 at 1pm. It then hit 86 at 2pm and 94 at 3pm.

Air quality is in the moderate range when the PSI is between 51 to 100, and enters the unhealthy level when PSI is between 101 and 200.